Efficient composite cement plant fire coal accelerant and preparation method thereof

Abstract

The invention relates to a high-efficiency composite cement plant fire coal accelerator and a preparation method thereof, and belongs to the technical field of clean combustion technology and catalysts, the high-efficiency composite cement plant fire coal accelerator comprises the following raw materials by mass: 30-45% of a nano metal oxide catalyst, 20-30% of a modified sulfur-fixing agent, 10-20% of an auxiliary agent, and the balance of water. The mass fraction of the transition metal salt combustion improver is 15%-25%, the mass fraction of the dispersion-stabilizer is 8%-12%, and the mass fraction of the rare earth synergist is 5%-10%. According to the high-efficiency composite cement plant fire coal accelerant and the preparation method thereof, through cooperation of the nano metal oxide catalyst, the modified sulfur-fixing agent, the transition metal salt combustion improver, the dispersion-stabilizer and the rare earth synergist, coal combustion can be promoted to achieve the coal saving effect, emission of harmful pollutants is reduced from the source, and environmental pollution is reduced. Remarkable economic benefits and environmental benefits are brought to a cement plant, and the modified sulfur-fixing agent enhances chemical adsorption with sulfur through the hydrophobic characteristic and achieves the effect that the sulfur-fixing rate is doubled through the oxidation catalysis effect of transition metal salt.

Description

Technical Field

[0001] The present invention relates to the fields of clean combustion technology and catalyst technology, in particular to a high-efficiency composite cement plant coal combustion accelerator and a preparation method thereof. Background Art

[0002] Amidst growing global energy demand and increasing environmental pressure, coal, as one of the world's most important energy sources, continues to account for a major share of global energy consumption. Coal is a primary energy source for the cement industry, providing heat for rotary kiln systems and supporting the high-temperature calcination of cement clinker. Coal usage accounts for 50%-55% of total energy consumption in cement production, making it the most important fuel. During the high-temperature calcination of cement clinker, coal combustion is affected by coal quality and kiln process parameters, and some pulverized coal may not be fully burned, resulting in energy waste and increased costs. Coal combustion also releases large amounts of sulfur dioxide, nitrogen oxides, and dust, making it a major source of pollution in the cement industry. Currently, countries are increasingly stringent in their regulations on industrial pollutants and carbon emissions, increasing environmental pressure on cement companies. Improving combustion technology and optimizing coal fuels are essential to meeting these standards. Therefore, improving coal utilization efficiency and reducing environmental burden are inevitable trends in the industry's development, providing a broad market opportunity for the research and development and promotion of coal combustion accelerators.

[0003] Coal combustion promoters refer to chemical additives that can improve the combustion characteristics of coal, promote the full combustion of coal and reduce the emission of harmful gases. These promoters reduce the ignition temperature of coal, increase the combustion reaction rate, promote the release of volatile matter in coal and improve the characteristics of coal ash through physical and chemical means, thereby improving the combustion efficiency of coal and reducing pollutant emissions. At present, many types of coal combustion promoters have been proposed, mainly including metal salts, inorganic compounds, and certain organic chemical additives. These promoters react with coal through different physical and chemical effects to optimize the combustion characteristics of coal.

[0004] However, existing coal combustion promoters still have certain limitations in improving combustion efficiency and reducing pollutant emissions. For example, the single-component catalyst has limited functionality and is difficult to meet the requirements of catalysis, sulfur fixation, and dispersion. The sulfur fixation agent is easily sintered and deactivated at high temperatures, and the actual sulfur fixation efficiency is less than 40%. Nitrate combustion promoters are prone to moisture absorption and agglomeration, and excessive use may increase NO x Therefore, a high-efficiency composite cement plant coal combustion accelerator and a preparation method thereof are proposed to solve the above problems. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a high-efficiency composite cement plant coal combustion accelerator and a preparation method thereof, which has the advantages of taking into account both combustion efficiency and reducing pollutant emissions, and solves the problem that existing accelerators still have certain limitations in improving combustion efficiency and reducing pollutant emissions.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a high-efficiency composite cement plant coal combustion accelerator, comprising the following raw materials in percentage by weight: a nano-metal oxide catalyst having a mass fraction of 30% to 45%, a modified sulfur-fixing agent having a mass fraction of 20% to 30%, a transition metal salt combustion improver having a mass fraction of 15% to 25%, a dispersant-stabilizer having a mass fraction of 8% to 12%, and a rare earth synergist having a mass fraction of 5% to 10%.

[0007] Furthermore, the nano metal oxide catalyst is a ternary composite oxide of iron, manganese and cerium, and the nano metal oxide catalyst also includes a Pt / CeO2 core-shell structure with a mass fraction of 1% and red mud with a mass fraction of 5%.

[0008] Furthermore, the modified sulfur-fixing agent is hydroxylated CaCO3 modified by silane coupling agent KH-550.

[0009] Furthermore, the transition metal salt includes one or more of chloride, nitrate, sulfate, oxalate, and manganate of a transition metal, the transition metal salt also includes potassium permanganate, and the transition metal includes one or more of iron, cobalt, nickel, copper, zinc, and manganese.

[0010] Furthermore, the dispersant-stabilizer is a composite product of polycarboxylate ammonium salt (molecular weight 2000-5000Da) and trivalent iron ion exchange type nano zeolite molecular sieve, the pore size of the trivalent iron ion exchange type nano zeolite molecular sieve is 0.55nm, and the dispersant-stabilizer also includes 2% by mass of carbon nanotube grafted polycarboxylate ammonium salt.

[0011] Furthermore, the rare earth synergist includes one or more of yttrium nitrate and lanthanum nitrate, and the rare earth synergist also includes ytterbium nitrate.

[0012] The present invention also provides a method for preparing a high-efficiency composite cement plant coal combustion accelerator, comprising the following steps:

[0013] S1. Preparation of nano-metal oxide catalysts: first preparing a solution, then gelling the solution, and finally calcining to obtain Fe-Mn-Ce-O composite oxide;

[0014] S2. Preparation of modified sulfur-fixing agent: CaCO3 powder was mixed with 5wt% KH-550 ethanol solution, ultrasonicated for 1 h with an ultrasonic power of 300 W, and then vacuum dried at 80°C for 4 h to obtain hydrophobic CaCO3.

[0015] S3: Pre-mix the transition metal salts and mix them using a ball mill for 1 h.

[0016] S4, a dispersant-stabilizer composite, polycarboxylate ammonium salt and trivalent iron ion exchange type nano zeolite molecular sieve are dry mixed in a mass ratio of 1:2, and 2% silane coupling agent KH-550 is added to enhance interface bonding.

[0017] S5. Add the above components in proportion to a planetary ball mill, add and add 5% polyvinyl alcohol (PVA) as a binder, and the accelerator is 1-3 mm microspheres with a compressive strength of ≥10 MPa.

[0018] Furthermore, the solution preparation process in S1 is specifically as follows: Fe(NO3)3·9H2O, Mn(CH3COO)2·4H2O, and Ce(NO3)3·6H2O are dissolved in an ethanol-water mixed solvent at a metal molar ratio of 2:1:1, and then citric acid (metal ions: citric acid = 1:1.5) is added, stirred at 80°C until a gel is formed, calcined at 500°C for 3h, and N2-H2 mixed gas (95:5) is introduced during the calcination stage to inhibit the growth of CeO2 grains. After calcination at 500°C, hydrofluoric acid vapor etching is added with a concentration of 5% and a time of 30min to form a mesoporous structure.

[0019] Furthermore, when adding citric acid, 0.5% graphene quantum dots with a particle size of less than 5 nm are added as an electron transport medium.

[0020] Furthermore, a rare earth synergist needs to be added to the S5, and a silane hydrophobic film is sprayed after the granulation is completed.

[0021] Compared with the prior art, the present invention provides a high-efficiency composite cement plant coal combustion accelerator and a preparation method thereof, which has the following beneficial effects:

[0022] 1. This high-efficiency composite cement plant coal combustion accelerator and its preparation method, through the combination of nano metal oxide catalyst, modified sulfur-fixing agent, transition metal salt combustion aid, dispersant-stabilizer and rare earth synergist, can promote coal combustion to achieve the effect of saving coal, reduce the emission of harmful pollutants at the source, and bring significant economic and environmental benefits to cement plants.

[0023] 2. This high-efficiency composite cement plant coal combustion accelerator and its preparation method: the modified sulfur-fixing agent enhances the chemical adsorption of sulfur through its hydrophobic properties, combined with the oxidative catalytic effect of transition metal salts, to double the sulfur-fixing rate. The microsphere structure sprayed with a silane hydrophobic film maintains its integrity under the high-temperature environment of the kiln, which can avoid crusting and coking.

[0024] 3. This high-efficiency composite cement plant coal combustion accelerator and its preparation method promote the full combustion of coal in the cement plant through the catalyst, thereby improving the combustion characteristics of coal, reducing the ignition temperature of coal, increasing the combustion reaction rate, promoting the release of volatile matter in coal, and improving the characteristics of coal ash, significantly improving the combustion efficiency and burnout rate of coal, and ensuring efficient energy utilization. Through extensive comparative test verification, the catalyst has demonstrated a wide adaptability to different types of coal, including coking coal, gas coal, lean coal, anthracite, lignite and even biofuels, and can achieve excellent catalytic effects. More importantly, the raw materials for the preparation of the catalyst completely exclude solid hazardous wastes, ensuring the safety and environmental protection of its use. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] A high-efficiency composite cement plant coal combustion accelerator in this embodiment includes the following raw materials in percentage by weight: a nano metal oxide catalyst with a mass fraction of 30% to 45%, a modified sulfur-fixing agent with a mass fraction of 20% to 30%, a transition metal salt combustion aid with a mass fraction of 15% to 25%, a dispersant-stabilizer with a mass fraction of 8% to 12%, and a rare earth synergist with a mass fraction of 5% to 10%.

[0027] In addition, the nano metal oxide catalyst is a ternary composite oxide of iron, manganese and cerium. Ferric oxide can reduce the ignition temperature of coal powder and accelerate the carbon-oxygen reaction. The mechanism of action of manganese dioxide is to catalyze volatilization and analysis, reducing the activation energy by 32-45°C. Cerium dioxide promotes oxygen migration through the oxygen vacancy effect and improves the burnout rate. The nano metal oxide catalyst also includes a Pt / CeO2 core-shell structure with a mass fraction of 1% and red mud with a mass fraction of 5%. TiO2 in the red mud can reduce the clinker liquid phase appearance temperature by 50 to 100°C, and Fe2O3 enhances the oxygen vacancy migration efficiency; after synergizing with CeO2, the burnout temperature is reduced by 20-30°C. The modified sulfur-fixing agent is hydroxylated CaCO3 modified by silane coupling agent KH-550. The silane coupling agent forms Si-O-Ca bonds on the surface of CaCO3 to improve hydrophobicity. The hydroxyl group enhances the chemical adsorption with SO2, thereby promoting the improvement of the sulfur-fixing rate.

[0028] It should be further explained that the transition metal salt includes one or more of chloride, nitrate, sulfate, oxalate and manganate of the transition metal, and the transition metal salt also includes potassium permanganate, which is used to release active oxygen and reduce the burnout temperature. The transition metal includes one or more of iron, cobalt, nickel, copper, zinc and manganese. Lead-zinc tailings can also be used to replace part of the nitrate, which contains 15% to 20% ZnO, to reduce the cost of raw materials and introduce Zn. 2+ Mineralizer.

[0029] In addition, the dispersant-stabilizer is a composite product of polycarboxylate ammonium salt (molecular weight 2000-5000Da) and trivalent iron ion exchange type nano zeolite molecular sieve. The pore size of the trivalent iron ion exchange type nano zeolite molecular sieve is 0.55nm, which can enhance the Hg / As adsorption capacity. The dispersant-stabilizer also includes a carbon nanotube grafted polycarboxylate ammonium salt with a mass fraction of 2%. The carbon nanotube grafted polycarboxylate ammonium salt can improve the dispersion stability of nanoparticles and prevent agglomeration. The rare earth synergist includes one or more of yttrium nitrate and lanthanum nitrate. The rare earth synergist also includes ytterbium nitrate.

[0030] This embodiment also provides a method for preparing a high-efficiency composite cement plant coal combustion accelerator, comprising the following steps:

[0031] S1. Preparation of nano-metal oxide catalysts: first preparing a solution, then gelling the solution, and finally calcining to obtain Fe-Mn-Ce-O composite oxide;

[0032] S2. Preparation of modified sulfur-fixing agent: CaCO3 powder was mixed with 5wt% KH-550 ethanol solution, ultrasonicated for 1 h with an ultrasonic power of 300 W, and then vacuum dried at 80°C for 4 h to obtain hydrophobic CaCO3.

[0033] S3: Pre-mix the transition metal salts and mix them using a ball mill for 1 h.

[0034] S4, a dispersant-stabilizer composite, polycarboxylate ammonium salt and trivalent iron ion exchange type nano zeolite molecular sieve are dry mixed in a mass ratio of 1:2, and 2% silane coupling agent KH-550 is added to enhance interface bonding.

[0035] S5. Add the above components in proportion to a planetary ball mill, add and add 5% polyvinyl alcohol (PVA) as a binder, and the accelerator is 1-3 mm microspheres with a compressive strength of ≥10 MPa.

[0036] It should be further explained that the solution preparation process in S1 is specifically to add Fe(NO3) v·9H2O, Mn(CH3COO)2·4H2O, and Ce(NO3)3·6H2O were dissolved in an ethanol-water mixed solvent at a metal molar ratio of 2:1:1, and then citric acid (metal ion: citric acid = 1:1.5) was added and stirred at 80°C until a gel was formed. The mixture was calcined at 500°C for 3 h. During the calcination stage, a N2–H2 mixed gas (95:5) was introduced to inhibit the growth of CeO2 grains. After calcination at 500°C, hydrofluoric acid vapor etching was added with a concentration of 5% for 30 min to form a mesoporous structure.

[0037] In addition, 0.5% graphene quantum dots with a particle size of <5 nm are added as an electron transport medium when adding citric acid. A rare earth synergist is also added to S5. After granulation, a silane hydrophobic film is sprayed.

[0038] In this embodiment, the synergistic effect of nano-iron-manganese-cerium ternary composite oxide, Pt / CeO2 core-shell structure and rare earth synergist significantly reduces the ignition point of coal powder and improves the burnout rate. The mesoporous structure formed by the nanocatalyst through hydrofluoric acid etching and the electron transport effect of graphene quantum dots accelerate oxygen diffusion and carbon activation, thereby reducing the activation energy of coal powder combustion.

[0039] It should be noted that through the coordinated innovation of nano-catalysis, solid sulfur modification, dispersion stabilization and other technologies, coal combustion can be promoted to achieve the effect of saving coal. Microsphere granulation can withstand the mechanical impact of pneumatic conveying and adapt to the pneumatic conveying system, avoiding the clogging and dust problems of traditional powder accelerators.

[0040] Example 1: Anthracite application in a cement plant

[0041] This embodiment provides a catalyst for coal combustion, comprising the following raw materials in weight percentage: 40% nanocatalyst, 25% modified sulfur-fixing agent, 20% composite combustion improver, 10% dispersant-stabilizer, and 5% rare earth synergist;

[0042] This embodiment provides a catalyst for coal combustion, which is applied to a cement plant. The coal type is anthracite. The specific industrial analysis data parameters are: ash content 25.3%, volatile matter 9.8%, sulfur content 1.6%, and calorific value 23.5MJ / kg.

[0043] This embodiment provides a catalyst for coal combustion, which is applied to a cement plant. The coal type is anthracite, and the addition amount is 0.3‰ of the coal mass. The catalyst and coal powder are simultaneously delivered to the decomposition furnace, and the decomposition furnace temperature is 1000°C.

[0044] The test results are shown in Table 1.

[0045] As can be seen from Table 1, the coal combustion accelerator of the present invention has excellent performance in improving the coal combustion efficiency of cement plants and reducing pollutant emissions, and is a high-efficiency composite coal combustion accelerator for cement plants.

[0046] Table 1 Test results

[0047] index Blank group Experimental group Rate of change Thermal efficiency (%) 61.5 66.5 +8.1％ <![CDATA[SO2 emissions (ppm)]]> 186.0 155.3 -16.5％ <![CDATA[NOx(mg / Nm 3 )]]> 84.6 60.4 -28.6％

[0048] Example 2: Industrial test of accelerator (compared with traditional accelerator)

[0049] The experiment was conducted on the basis of Example 1, except that: in this example, a traditional accelerator was used instead of a blank group to compare the effects with the accelerator of the present invention.

[0050] The test results are shown in Table 2.

[0051] As shown in Table 2, the coal combustion accelerator of the present invention is superior to the traditional accelerator in improving the coal combustion efficiency of cement plants and reducing pollutant emissions.

[0052] Table 2 Test results

[0053] index Traditional accelerators Accelerator of the present invention Improvement Thermal efficiency (%) +5.1％ +8.1％ +58.8％ <![CDATA[SO2 emission reduction rate]]> 12.6％ 16.5％ +30.9％ NOx emission reduction rate 22.6％ 28.6％ +26.5％

[0054] Example 3: Process parameter optimization verification

[0055] The experiment was conducted on the basis of Example 1, except that: in this embodiment, the addition ratio of nano metal oxide catalyst was set to 30%, 40%, and 50%; the combustion temperature was set to 800°C, 1000°C, and 1200°C. A total of 9 groups of comparative experiments were conducted to compare the effects.

[0056] The test results are shown in Table 3.

[0057] As shown in Table 3, the 40% nano-metal oxide catalyst ratio in the coal combustion accelerator of the present invention has the best comprehensive performance and the best high-temperature adaptability.

[0058] Table 3 Test results

[0059] Catalyst ratio 800℃ thermal efficiency Thermal efficiency at 100℃ 1200℃ thermal efficiency 30％ 62.9％ 64.1％ 64.9％ 40％ 64.3％ 66.5％ 67.9％ 50％ 63.3％ 65.4％ 65.6％

[0060] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0061] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A high-efficiency composite cement plant coal combustion accelerator, characterized in that: The invention comprises the following raw materials in percentage by weight: a nano metal oxide catalyst having a mass fraction of 30% to 45%, a modified sulfur-fixing agent having a mass fraction of 20% to 30%, a transition metal salt combustion improver having a mass fraction of 15% to 25%, a dispersant-stabilizer having a mass fraction of 8% to 12%, and a rare earth synergist having a mass fraction of 5% to 10%.

2. The high-efficiency composite cement plant coal combustion accelerator according to claim 1, characterized in that: The nano metal oxide catalyst is a ternary composite oxide of iron, manganese and cerium. The nano metal oxide catalyst also includes a Pt / CeO2 core-shell structure with a mass fraction of 1% and red mud with a mass fraction of 5%.

3. The high-efficiency composite cement plant coal combustion accelerator according to claim 1, characterized in that: The modified sulfur-fixing agent is hydroxylated CaCO3 modified by silane coupling agent KH-550.

4. The high-efficiency composite cement plant coal combustion accelerator according to claim 1, characterized in that: The transition metal salt includes one or more of chloride, nitrate, sulfate, oxalate, and manganate of a transition metal; the transition metal salt also includes potassium permanganate; and the transition metal includes one or more of iron, cobalt, nickel, copper, zinc, and manganese.

5. The high-efficiency composite cement plant coal combustion accelerator according to claim 1, characterized in that: The dispersant-stabilizer is a composite product of polycarboxylic acid ammonium salt (molecular weight 2000-5000Da) and trivalent iron ion exchange type nano zeolite molecular sieve, the pore size of the trivalent iron ion exchange type nano zeolite molecular sieve is 0.55nm, and the dispersant-stabilizer also includes carbon nanotube grafted polycarboxylic acid ammonium salt with a mass fraction of 2%.

6. The high-efficiency composite cement plant coal combustion accelerator according to claim 1, characterized in that: The rare earth synergist includes one or more of yttrium nitrate and lanthanum nitrate, and the rare earth synergist also includes ytterbium nitrate.

7. The method for preparing the high-efficiency composite cement plant coal combustion accelerator according to any one of claims 1 to 6, comprising the following steps: S1. Preparation of nano-metal oxide catalysts: first preparing a solution, then gelling the solution, and finally calcining to obtain Fe-Mn-Ce-O composite oxide; S2. Preparation of modified sulfur-fixing agent: CaCO3 powder was mixed with 5wt% KH-550 ethanol solution, ultrasonicated for 1 h with an ultrasonic power of 300 W, and then vacuum dried at 80°C for 4 h to obtain hydrophobic CaCO3. S3: Pre-mix the transition metal salts and mix them using a ball mill for 1 h. S4, a dispersant-stabilizer composite, polycarboxylate ammonium salt and trivalent iron ion exchange type nano zeolite molecular sieve are dry mixed in a mass ratio of 1:2, and 2% silane coupling agent KH-550 is added to enhance interface bonding. S5. Add the above components in proportion to a planetary ball mill, add and add 5% polyvinyl alcohol (PVA) as a binder, and the accelerator is 1-3 mm microspheres with a compressive strength of ≥10 MPa.

8. The high-efficiency composite cement plant coal combustion accelerator and preparation method thereof according to claim 7, characterized in that: The solution preparation process in S1 is specifically as follows: Fe(NO3)3·9H2O, Mn(CH3COO)2·4H2O, and Ce(NO3)3·6H2O are dissolved in an ethanol-water mixed solvent at a metal molar ratio of 2:1:1, and then citric acid (metal ions: citric acid = 1:1.5) is added, stirred at 80°C until a gel is formed, calcined at 500°C for 3h, and N2-H2 mixed gas (95:5) is introduced during the calcination stage to inhibit the growth of CeO2 grains. After calcination at 500°C, hydrofluoric acid vapor etching is added with a concentration of 5% and a time of 30min to form a mesoporous structure.

9. The high-efficiency composite cement plant coal combustion accelerator and preparation method thereof according to claim 8, characterized in that: When adding citric acid, 0.5% graphene quantum dots with a particle size of less than 5 nm are added as an electron transport medium.

10. The high-efficiency composite cement plant coal combustion accelerator and preparation method thereof according to claim 7, characterized in that: A rare earth synergist needs to be added to the S5, and a silane hydrophobic film is sprayed after granulation is completed.